 
function index = randIndex(maxIndex,len) 
%randomly, non-repeatedly select LEN integers from 1:MAXINDEX 
 if len > maxIndex 
    index = []; 
    return 
 end 
index = zeros(1,len); 
available = 1:maxIndex; 
rs = ceil(rand(1,len).*(maxIndex:-1:maxIndex-len+1)); 
for p = 1:len 
    while rs(p) == 0 
        rs(p) = ceil(rand(1)*(maxIndex-p+1)); 
    end 
    index(p) = available(rs(p)); 
    available(rs(p)) = []; 
end

end